1. Field of the Invention
The present invention relates to a window antenna for a vehicle and, more particularly, to a window antenna which can reliably receive a TV broadcast wave.
2. Description of the Prior Art
As is conventionally known, a radio-reception antenna wire can be provided on a surface on the passenger compartment side of the rear windshield of a vehicle, in addition to a plurality of defogging heater wires. Such an antenna wire is normally tuned to sensitively receive a radio broadcast signal in the AM and FM bands, but cannot receive a TV broadcast signal. Therefore, in order to receive both radio and TV broadcast signals in the vehicle compartment, a special-purpose antenna for receiving a TV broadcast signal must be additionally provided.
It is generally difficult to mount a broad-band Yagi antenna for receiving a TV broadcast signal on a vehicle. Therefore, a TV antenna wire must be arranged on a surface of the vehicle, as in the case of an AM/FM window antenna. However, since the vehicle body is formed mainly of an iron plate and the rear windshield is occupied by the radio antenna wire, possible mounting areas for the TV antenna are limited. It is undesirable to mount the antenna wire on the front windshield, with regard to the field of view.
Even if the TV antenna can be mounted, a TV broadcasting frequency extends over a wide range, for example in Japan, from a low frequency range (90 to 108 MHz of channel Nos. 1 to 3) to a high frequency range (170 to 222 MHz of channel Nos. 4 to 12). Therefore, it is very difficult to cover such a broad bandwidth as well as a UHF band with a single antenna.